Known in the art is the production of cements by using, apart from Portland cement clinker and gypsum, additionally mineral additives, the weight fraction of which accounts for 5 to 60% by mass. Introduction of active mineral additives into cement makes it possible to reduce the cost of the latter and in some cases to modify the construction and engineering properties of cement (for instance, cement hardening kinetics, heat release, setting periods, resistance to sulphates).
The production of cement may involve the use of both artificial and natural mineral additives in an active mineral component. The natural mineral additives may include: diatomite, tripolite, opoka, "gliesh". The artificial mineral additives include blast furnace and phosphatic slags.
When blast furnace and phosphatic slags are used as mineral additives to cements, the slags are subjected to granulation by dispersing the melt of these slags and their sharp cooling. However, the hydraulic activity and whiteness index of the slags in this case are low.
The hydraulic activity of granulated blast furnace slags can be increased by their heat treatment at a temperature of 700.degree. C. for 1-5 minutes (I. N. Rogacheva "Research and development in the field of technology of water-resistant magnesia cement", Kharkovsky Politekhnichesky Institut, 1975, pp. 12-14). This is accompanied by a partial crystallization of slag glass and an increase in the defectiveness of the structure and, as a result, the activity of slags rises, thereby providing a subsequent increase in the strength of cement by 2-3 MPa. The whiteness of the additive produced amounts to 60%.